Insulation for electrical apparatus



W. J. SHACKELTON.

INSULATION FOB ELECTRICAL APPARATUS. APPLICATION FILED AUG. 16. I911.

Patented May 13, 1919.

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UNITED ST ES PATENT oFFIoE.

WILLIAM J. SHACKELTON, OF SCOTCH PLAINS, NEW JERSEY, ASSIGNOR T WESTERN ELECTRIC COMPANY, INCORPORATED, OF- NEW YORK, N. Y., A CORPORATION OF NEW YORK.

INSULATION FOR ELECTRICAL APPARATUS.

Specification of-Letters Patent.

Patented May 13, 1919.

Application filed August 16, 1917. Serial No. 186,539.

To all whom it may concern:

Be it known that I, WILLIAM J. SHACKEL- TON, a citizen of the United States,residing at Scotch Plains, in'the county of Union and State of New Jersey, have invented certain new and useful Improvements in Insulation for Electrical Apparatus, of which the following is' a full, clear, concise, and exact description.

This invention relatas to insulation for electrical apparatus and to a method for manufacturing the same, and more particularly to insulation adapted for use in transformers, repeating) coils, loading coils and similar apparatus. 7

The general object of the invention is to provide a. new and improved form of insulation having uniformly high dielectric strength and yet occupying a comparatively small amount of space;

The insulation heretofore purpose above mentioned has usually consolid material, such as fiber orhard rubber tubes; or of flexible material of high dielectrio strength, such as varnished muslin tape applied in layers between the parts to be insulated; or of material having inherently low dielectric strength impregnated with an insulating compound which is comparatively rigid under service conditions, such as cotton fabric impregnated with rosin. Each of these insulators ordinarily requires a comparatively large amount ofspace in order to provide high dielectric strength and is, therefore, not entirely satisfactory for all used for the having any number of superimposed wind- Referring to the drawing, the core of the repeating coil is shown at as composed of any suitable magnetic material, such as insulated iron wire wound in the form of a mug.

The core 5 is wrapped with a layer of any suitable insulating material, such as cotton tape 6 ing 7 of insulated copper wire is wound in any well-known manner. The partially completed coil is then impregnated with a suitable. insulating compound. The next step in the process of manufacture is the applying/of a layer of insulating material of high dielectric strength which shall serve to separate the inner winding and upon this tape the inner wind- 7 and the outer winding hereinafter mentioned. The

present invention resides in'this insulating layer and the method of applying it now to be described. sisted either of comparatively inflexible purposes; This element of space is exceed- Y ingly important in certain classes of apparatus, such as telephone transformers and repeating coils where the leakage induc- The partially completed coil is preferably wound with a layer of impervious or partially impervious material 8, such as over-- lapping varnished muslin tape. Upon this is then wound a uniform thickness of insulating filler which may be in the form of a cotton tape 9. The coil is then preferably immersed in a heated molten insulating compound of high dielectric strength which may comprise a normally plastic or highly viscous mixture of rosin and rosin oil. The compound with the coil therein is then allowed to cool to its normally plastic or highly viscous semi-solid state. It is then reheated sufficiently to melt off the excessive amount of insulating compound which would otherwise adhere to the tape 9, and

the coil is withdrawn from the compound tances of the windings are predominating causes of low efiiciency.

The preferredembodiment of this invention is illustrated in the drawing, wherein is shown a ring-shaped repeating two windings insulated from one insulation made in accordance present invention, the coil being cut away to more clearly show the tion. While a ring-shaped coil having two windings is shown in the drawing, it will be clear that this invention is applicable to solenoidal or other shaped coils and to co-ils another by with the partially coil having construcdisturbed covered with a uniform thickness of the insulating compound which is intimately intermingled with the cotton fabric. The coil is then wound with a layer of impervious or partially impervious material such as overlapping varnished muslin tape 10. The tape 9, impregnated with and covered by the insulating compound of high dielectric strength, is thus held between the impervious or partially impervious layers of varnished muslin tape 8 and 10, and cannot be by future treatment of the repeating coil either in subsequent steps of manufact lire or in uses which it may be i put, the impervious inclosing .layers 8 and," 1 0 confine the plastic or viscous insulatlng compound toits predetermined location between the windings and prevent 'it from es-.

caping by dilfusing into the adjacent Wind copper wir is then wound on, and is covered byy suitable insulating material,

The outer winding 11 of insulated such as overlapping cotton tape 12. The

coil may thenbe impregnated with a suitable insulating compound in any well-known V manner. When so constructed, a repeating coil is provided in which the windings are separated by insulating material of high dielectric strength occupying comparatively 20. of a coil, that which was applied in accordj of insulating compound.

- a plurality of wind insulated from one another.

small space.

In actual commercial coils, it has been found that, withthe same thickness of insulating material between the two windings "ance with this invention broke down at approximately one and two thirds times the voltage which broke down that applied by the ordinary heretofore *known methods.

Modifications of the exact structure and process hereinbefore described may obviously be made'without'departing from the scope of this invention as setforthin theaccompanying claims and it is to be understood that wherever the word transformer'is used alone in the specification (and claims, it is intended to include'repeating coils, loading coils :and other elec trical apparatus wherein different .parts are What is claimedis: 1.. In at ansformer, alayer of diffusive insulating compound, and a plurality of lay-,

ers of material impervious to said compound forming a'compartment inclosing saidlayer .2. In a transformer,

' ings, insulating means between said wind- .45 ing compound, and a plurality of layers of material impervious to said compound form- 1 ing a compartment inclosing said-layer of 1 insulating compound.

ings comprising a layer of diifusive' insulat- 1 '3. .In a transformer, a layer of plastic or 7 highly viscous insulating compound, -and a plurality of layers of material substantially impervious tosaid compound, said layer of insulating compound being retained between the layers of impervious material.

4;.A transformer as'specified in claim in combination with an insulating filler intimately associated. with said plastic or "highlyviscousinsulating compound.

5. In a transformer, a plurality of windings, a plurality of layers of varnished musv lin, tape therebetween, and a layer of insulating compound between said layers of varnished'muslin, said insulating compound comprising a highly viscous mixture of rosin and rosin oil.

8. A transformer as specified in claim 7 in I combination with a layer of cotton fabrlc intimately associated with said layer of insulating compound.

' 9. The method of insulating superimposed windings which consists in applying a layer of impervious or partially impervious material over one. ofsaid windings, surrounding such layer with a suitable layer of plastic or highly viscous material of high dielectric strength, applying a second layer of over said plastic material, and superimposing a; second winding thereover.

10-. The method of insulating superimposed windings which consists in applying a layerof varnished muslin tape over one of said windings, immersing such partiallycompleted coil in a molten insulating compound of high. dielectric strength, allowing the compound to cool, reheating it sufiicien tly to. allow the removal of said partially completed coil therefrom, applying a second layer of varnished muslin tape, and superimposing a second winding thereover.

impervious or partially impervious material 11. The method of insulating a repeating coil having a plurality of superimposed windings, which consists in applying aJayer of varnished muslin over one of said wind- I ings, applying a layer of cotton fabric thereover, immersing such partlally completed coil in. a molten compound comprising a normally highly viscous mixture of rosin and rosin oil, allowing said molten compound to i cool before removing said partially completed coil therefrom, reheating said compound suificiently to allow the removal of said coil therefrom, applying a second layer of varnished muslin thereover, and superimposing a second winding thereupon.

In witness whereof, I hereunto subscribe my name this 14th day of August, A. D.

I LIAMS. SHACKELTON. 

